The effect of TRH, cyproheptadine and pimozide on the growth hormone response to intramuscular glucagon.
Glucagon-induced growth hormone (GH) secretion was studied in healthy subjects under basal conditions (n = 18), and when treated with TRH (n = 10), cyproheptadine (n = 8) and pimozide (n = 6). With glucagon alone, the mean serum GH level significantly increased at 150 minutes and at 180 minutes. TRH administered as a bolus injection completely suppressed the GH response to glucagon. Cyproheptadine pretreatment resulted in a substantial suppression of the GH response to glucagon. A significant difference between basal and post-cyproheptadine GH levels was observed at 150 minutes after glucagon. Pimozide pretreatment was followed by a reduction of GH response to glucagon, but the difference between control and pimozide-treated groups was not significant. In conclusion, it is proposed that glucagon-induced GH secretion is at least partly mediated via serotoninergic mechanisms while significant dopaminergic involvement does not seem probable. It is further suggested that TRH plays a substantial inhibitory role in glucagon-stimulated SH secretion.
D000328:Adult; D003533:Cyproheptadine / Q000494:pharmacology*; D004298:Dopamine / Q000502:physiology; D005260:Female; D005934:Glucagon / Q000008:administration & dosage / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D010868:Pimozide / Q000494:pharmacology*; D012701:Serotonin / Q000502:physiology; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D010868:Pimozide; D003533:Cyproheptadine; D012701:Serotonin; D013973:Thyrotropin-Releasing Hormone; D013006:Growth Hormone; D005934:Glucagon; D004298:Dopamine